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author | Alexei Starovoitov <ast@plumgrid.com> | 2015-06-04 10:11:54 -0700 |
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committer | David S. Miller <davem@davemloft.net> | 2015-06-07 02:01:33 -0700 |
commit | d691f9e8d4405c334aa10d556e73c8bf44cb0e01 (patch) | |
tree | 295b1d647364407c42990d916358a72381f4d534 /samples/bpf/test_verifier.c | |
parent | 3431205e03977aaf32bce6d4b16fb8244b510056 (diff) | |
download | linux-stable-d691f9e8d4405c334aa10d556e73c8bf44cb0e01.tar.gz linux-stable-d691f9e8d4405c334aa10d556e73c8bf44cb0e01.tar.bz2 linux-stable-d691f9e8d4405c334aa10d556e73c8bf44cb0e01.zip |
bpf: allow programs to write to certain skb fields
allow programs read/write skb->mark, tc_index fields and
((struct qdisc_skb_cb *)cb)->data.
mark and tc_index are generically useful in TC.
cb[0]-cb[4] are primarily used to pass arguments from one
program to another called via bpf_tail_call() which can
be seen in sockex3_kern.c example.
All fields of 'struct __sk_buff' are readable to socket and tc_cls_act progs.
mark, tc_index are writeable from tc_cls_act only.
cb[0]-cb[4] are writeable by both sockets and tc_cls_act.
Add verifier tests and improve sample code.
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'samples/bpf/test_verifier.c')
-rw-r--r-- | samples/bpf/test_verifier.c | 84 |
1 files changed, 82 insertions, 2 deletions
diff --git a/samples/bpf/test_verifier.c b/samples/bpf/test_verifier.c index 12f3780af73f..693605997abc 100644 --- a/samples/bpf/test_verifier.c +++ b/samples/bpf/test_verifier.c @@ -29,6 +29,7 @@ struct bpf_test { ACCEPT, REJECT } result; + enum bpf_prog_type prog_type; }; static struct bpf_test tests[] = { @@ -743,6 +744,84 @@ static struct bpf_test tests[] = { .errstr = "different pointers", .result = REJECT, }, + { + "check skb->mark is not writeable by sockets", + .insns = { + BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_1, + offsetof(struct __sk_buff, mark)), + BPF_EXIT_INSN(), + }, + .errstr = "invalid bpf_context access", + .result = REJECT, + }, + { + "check skb->tc_index is not writeable by sockets", + .insns = { + BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_1, + offsetof(struct __sk_buff, tc_index)), + BPF_EXIT_INSN(), + }, + .errstr = "invalid bpf_context access", + .result = REJECT, + }, + { + "check non-u32 access to cb", + .insns = { + BPF_STX_MEM(BPF_H, BPF_REG_1, BPF_REG_1, + offsetof(struct __sk_buff, cb[0])), + BPF_EXIT_INSN(), + }, + .errstr = "invalid bpf_context access", + .result = REJECT, + }, + { + "check out of range skb->cb access", + .insns = { + BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1, + offsetof(struct __sk_buff, cb[60])), + BPF_EXIT_INSN(), + }, + .errstr = "invalid bpf_context access", + .result = REJECT, + .prog_type = BPF_PROG_TYPE_SCHED_ACT, + }, + { + "write skb fields from socket prog", + .insns = { + BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1, + offsetof(struct __sk_buff, cb[4])), + BPF_JMP_IMM(BPF_JGE, BPF_REG_0, 0, 1), + BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1, + offsetof(struct __sk_buff, mark)), + BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1, + offsetof(struct __sk_buff, tc_index)), + BPF_JMP_IMM(BPF_JGE, BPF_REG_0, 0, 1), + BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_1, + offsetof(struct __sk_buff, cb[0])), + BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_1, + offsetof(struct __sk_buff, cb[2])), + BPF_EXIT_INSN(), + }, + .result = ACCEPT, + }, + { + "write skb fields from tc_cls_act prog", + .insns = { + BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1, + offsetof(struct __sk_buff, cb[0])), + BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_0, + offsetof(struct __sk_buff, mark)), + BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1, + offsetof(struct __sk_buff, tc_index)), + BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_0, + offsetof(struct __sk_buff, tc_index)), + BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_0, + offsetof(struct __sk_buff, cb[3])), + BPF_EXIT_INSN(), + }, + .result = ACCEPT, + .prog_type = BPF_PROG_TYPE_SCHED_CLS, + }, }; static int probe_filter_length(struct bpf_insn *fp) @@ -775,6 +854,7 @@ static int test(void) for (i = 0; i < ARRAY_SIZE(tests); i++) { struct bpf_insn *prog = tests[i].insns; + int prog_type = tests[i].prog_type; int prog_len = probe_filter_length(prog); int *fixup = tests[i].fixup; int map_fd = -1; @@ -789,8 +869,8 @@ static int test(void) } printf("#%d %s ", i, tests[i].descr); - prog_fd = bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, prog, - prog_len * sizeof(struct bpf_insn), + prog_fd = bpf_prog_load(prog_type ?: BPF_PROG_TYPE_SOCKET_FILTER, + prog, prog_len * sizeof(struct bpf_insn), "GPL", 0); if (tests[i].result == ACCEPT) { |